IBAN (International Bank Account Number)

Published on

31/08/2026

Updated on

03/09/2026

Reading time

4 min

Definition

The IBAN (International Bank Account Number) is the internationally standardized identifier for a payment account. Defined by the ISO 13616 standard, it replaces previously varied national account number formats with a machine-verifiable structure. The aim is to enable fully automated payment processing without the need for manual intervention.

While the BIC(opens in new tab) identifies the institution holding the account, the IBAN addresses the specific account.

Composition

The IBAN is a maximum of 34 alphanumeric characters long. The structure is always the same:

Component	Length	Contents
Country code	2	Country codes according to ISO 3166-1 alpha-2
Check digit	2	Check digit for the entire IBAN
BBAN	variable	nationally defined account identifier

The German IBAN is 22 characters long and consists of the country code DE, two check digits, the eight-digit bank code, and the account number, which is padded with zeros on the left to a length of ten digits.

The length varies by country—and is itself a criterion for checking

The BBAN is defined at the national level. Consequently, each country has a fixed—though unique—IBAN length. It ranges from 15 characters in Norway to 31 characters in Malta; the standard allows for up to 34.

Country	Code	Length
Norway	NO	15
Belgium	BE	16
Denmark, Finland, Netherlands	DK, FI, NL	18
Slowenia	SI	19
Austria, Estonia, Lithuania, Luxembourg	AT, EE, LT, LU	20
Croatia, Latvia, Liechtenstein, Switzerland	HR, LV, LI, CH	21
Germany, Bulgaria, Ireland, United Kingdom	DE, BG, IE, GB	22
Czech Republic, Romania, Sweden, Slovakia, Spain	CZ, RO, SE, SK, ES	24
Portugal	PT	25
Iceland	IS	26
France, Greece, Italy, Monaco	FR, GR, IT, MC	27
Poland, Hungary, Cyprus	PL, HU, CY	28
Malta	MT	31

Two practical implications:

The length is the first check. An IBAN with FR and 22 digits is incorrect even before a check digit is calculated. Every serious IBAN check therefore first looks up the expected length in the country directory.

Check digits: two methods, two purposes

This involves a mix-up that frequently arises in projects. A German IBAN contains two independent check digits.

The IBAN check digit

It occupies positions 3 and 4 and is calculated using the MOD 97-10 method in accordance with ISO/IEC 7064: the first four characters are moved to the end, all letters are replaced by numbers (A = 10 through Z = 35), and the resulting value is calculated modulo 97. The result must be 1.

This procedure is internationally standardized and reliably detects typos and transposed digits. However, it checks only the internal consistency of the character string.

The check digit of the account number in Germany

Independently of this, German account numbers feature their own check digit, which existed prior to the IBAN and remains unchanged within the BBAN. The Deutsche Bundesbank publishes the permissible calculation procedures—referred to as “check digit calculation methods for account numbers”—alongside the bank sort code file. The specific method used by each institution is indicated for every bank sort code. More than one hundred different procedures are permitted. Further details can be found in the article on check digit calculation for account numbers(opens in new tab).

Other countries handle this individually. Some also include a check digit in the BBAN—France has the clé RIB, Italy the leading CIN character, Spain two dígitos de control, and Belgium a modulo-97 check within the account number. Most countries do not use a national procedure.

With the introduction of Verification of Payee(opens in new tab), the relevance of these check digits has diminished.

Registration and Maintenance

The registration authority for ISO 13616 is SWIFT(opens in new tab). The IBAN Registry maintained there documents the national IBAN formats (length, structure of the BBAN, permitted characters) for over 80 countries and territories. It is the authoritative source for the length table above. Only national standards bodies or central banks can apply for registrations.

In Germany, the Bundesbank publishes IBAN rules alongside the methods for calculating check digits. These rules set out the requirements for payment service providers on how to derive the corresponding IBAN from an account number and bank code, and they take into account special cases such as mergers and institution-specific exceptions. Both files are updated regularly.

IBAN-only and IBAN-discrimination

Since February 1, 2016, the IBAN-only rule has applied within the SEPA(opens in new tab) area: the IBAN is sufficient for SEPA payments, and providing the BIC is no longer required. This is based on SEPA Regulation (EU) No. 260/2012.

Article 9 of the same regulation prohibits so-called IBAN discrimination: a payee may not reject an IBAN simply because it originates from another SEPA country. In practice, however, this still occurs—for instance, when counterparties accept only domestic IBANs for direct debits. Varying IBAN lengths are often the technical reason behind a rejection that appears to be based on business rules.

Virtual IBAN (vIBAN)

A virtual IBAN is an IBAN that does not correspond to a standalone account but instead points to a pooled or master account. Financial institutions and payment service providers use them to allocate incoming payments to individual customers or clients.

In May 2024, the EBA published a report highlighting a lack of transparency as well as risks regarding anti-money laundering and regulatory arbitrage—particularly where the country code of the vIBAN does not correspond to the customer’s actual place of establishment. Anti-Money Laundering Regulation (EU) 2024/1624 defines vIBANs at the EU level for the first time and attaches identification obligations to them.